CXCR4 and leukemia: Similarly, exosomes carry Fas ligand (FAS-L), NPM1, FLT3, matrix metallopeptidase 9 (MMP9), insulin-like growth factor type 1 receptor (IGF1-R), CXCR4, and chaperones to alter the BM microenvironment and to improve the survival of leukemia cells, especially LSCs (196, 197).